<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- <button>付博森</button> -->
     <input type="text">

     <div>哈哈哈哈哈</div>
</body>
</html>

<script>
    // var bth=document.querySelector('button');
    // bth.onclick=function(){
    //     alert('牛逼')
    // }

    var div=document.querySelector('div');
    var ipt=document.querySelector('input');

    div.onclick=function(){
        div.innerHTML='放假了'
    }
    ipt.onfocus=function(){
        ipt.value='付博森'
    }
    ipt.onblur=function(){
        ipt.value=''
    }
</script>